private void buttonGetOrdDet_Click(object sender, EventArgs e)
{
// Q1 step, get the data source
DataClassesOrderDetailDataContext myOrderDetail = new DataClassesOrderDetailDataContext();
// bind a combobox to an entity collection
// its like binding a combobox to a table in a DataSet. our DataContext has the whole table in it
// so we can bind it. Note this is ALL items, not the ones > 79, and note is in no order
comboBoxResults.DataSource = myOrderDetail.Products;
comboBoxResults.DisplayMember = "ProductName"; // as with all combo boxes or drop downs, you pick the "column" to show
comboBoxResults.ValueMember = "ProductID"; // and the hidden column which is usually a primary key
// Q2 step, define the query expression, since we don't want all the table, we want to subset it with a query
var orders = from myOrders in myOrderDetail.Order_Details
where myOrders.Quantity > 79
orderby myOrders.Product.ProductName ascending
select new { myOrders.Product.ProductName, myOrders.Quantity, myOrders.ProductID }; // these 3 fields are now available to us
// notice how Product name is again using the Association that LINQ build from the pre-existing SQL relationship
// bind a combobox to display our query results
comboBoxResults2.DataSource = orders;
comboBoxResults2.DisplayMember = "ProductName";
comboBoxResults2.ValueMember = "ProductID";
// bind same query results to dataGridView, but the dataGridView will show all the fields
dataGridViewResults.DataSource = orders;
dataGridViewResults.AutoResizeColumns();
dataGridViewResults.AlternatingRowsDefaultCellStyle.BackColor = Color.BlanchedAlmond;
}
private void buttonGetPrice_Click(object sender, EventArgs e)
{
// Q1 step, get the data source
DataClassesOrderDetailDataContext myOrderDetail2 = new DataClassesOrderDetailDataContext();
// Q2 step, define the query expression
int productID = (int)comboBoxResults2.SelectedValue;
var selectedProduct = (from myProducts in myOrderDetail2.Order_Details
where myProducts.ProductID == productID
select myProducts.UnitPrice).Max();
// not a unique value, so need to force to just one value, I used Max
textBoxProduct.Text = selectedProduct.ToString();
}
private void buttonGetOrdDet_Click(object sender, EventArgs e)
{
// Q1 step, get the data source
DataClassesOrderDetailDataContext myOrderDetail = new DataClassesOrderDetailDataContext();
// Q2 step, define the query expression
var orders = from myOrders in myOrderDetail.Order_Details
where myOrders.Quantity > 79
orderby myOrders.Product.ProductName ascending
select new { myOrders.Product.ProductName, myOrders.Quantity, myOrders.ProductID };
// create a new BindingSource object
myBinding = new BindingSource();
// bind the query to a Binding object
myBinding.DataSource = orders;
//attach the BindingSource to the DataGridView.
dataGridViewResults.DataSource = myBinding;
}
private void buttonGetPrice_Click(object sender, EventArgs e)
{
// Q1 step, get the data source
DataClassesOrderDetailDataContext myOrderDetail2 = new DataClassesOrderDetailDataContext();
int productID = (int)dataGridViewResults.CurrentCell.Value;
var selectedProduct = (from myProducts in myOrderDetail2.Order_Details
where myProducts.ProductID == productID
select new { myProducts.UnitPrice });
myBindingTB = new BindingSource();
// bind the query to a Binding object
myBindingTB.DataSource = selectedProduct;
//attach the BindingSource a textbox
textBoxProduct.Clear();
textBoxProduct.DataBindings.Clear();
textBoxProduct.DataBindings.Add("Text", myBindingTB, "UnitPrice", true);
//method props are: string property name, object data source, string dataMember, bool format (or don't format false)
}